A Novel Method for Estimating the Ambient Medium Density Around Distant Radio Sources from Their Observed Radio Spectra
arXiv:2011.10807 · doi:10.3847/1538-4357/ac116c
Abstract
The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FRII type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can estimate various physical parameters of the systems, including the density of the ambient medium into which the radio structure evolves. This, however, requires rather comprehensive observational information, i.e. sampling the broad-band radio continua of the targets at several frequencies, and imaging their radio structures with high resolution. Such observations are, on the other hand, not always available, especially for high-redshift objects. Here we analyze the best-fit values of the source physical parameters, derived from an extensive modeling of the largest currently available sample of FRII radio sources, for which good-quality multi-wavelength radio flux measurements could be collected. In the analyzed dataset, we notice a significant and non-obvious correlation between the spectral index of the non-thermal radio emission continuum, and density of the ambient medium. We derive the corresponding correlation parameters, and quantify the intrinsic scatter by means of Bayesian analysis. We propose that the discovered correlation could be used as a cosmological tool to estimate the density of ambient medium for large samples of distant radio galaxies. Our method does not require any detailed modeling of individual sources, and relies on limited observational information, namely the slope of the radio continuum between the rest-frame frequencies 0.4GHz and 5GHz, possibly combined with the total linear size of the radio structure.
Accepted for publication in the Astrophysical Journal
References in corpus (21)
- The eROSITA X-ray telescope on SRG
- Radio-Loudness of Active Galactic Nuclei: Observational Facts and Theoretical Implications
- Distant Radio Galaxies and their Environments
- Revisiting the Fanaroff-Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)
- On the Evolution of and High-Energy Emission from GHz-Peaked-Spectrum Sources
- A search for distant radio galaxies from SUMSS and NVSS: III. radio spectral energy distributions and the z-alpha correlation
- A representative survey of the dynamics and energetics of FRII radio galaxies
- High redshift FRII radio sources: large-scale X-ray environment
- A method of estimation of the dynamical age of FR II-type radio sources from multifrequency data
- On the dynamical evolution of hot spots in powerful radio loud AGNs
- Correlation between X-ray and radio absorption in compact radio galaxies
- Dynamical analysis of the complex radio structure in 3C 293: Clues on a rapid jet realignment in X-shaped radio galaxies
- The unrelaxed dynamical structure of the galaxy cluster Abell 85
- The Magnetic Field and Polarization Properties of Radio Galaxies in Different Accretion States
- Deciphering the Large-Scale Environment of Radio Galaxies in the Local Universe II. A Statistical Analysis of Environmental Properties
- On the Interaction of the PKS B1358-113 Radio Galaxy with the Abell 1836 Cluster
- Practical Bayesian optimization in the presence of outliers
- Link between radio-loud AGNs and host-galaxy shape
- RAiSERed: radio continuum redshifts for lobed AGNs
- On the Merging Cluster Abell 578 and Its Central Radio Galaxy 4C +67.13
- Extended Radio Structures and a Compact X-ray Cool-Core in the Cluster Source PKS 1353-341